Datasheet

_
+
V
DD
V
O+
V
O−
GND
6
5
8
7
To Battery
C
s
IN−
IN+
4
3
R
I
R
I
40 kΩ
40 kΩ
+
−
C
I
C
I
C
F
C
F
C
a
C
a
R
a
R
a
(1)
C
(BYPASS)
is optional
Bias
Circuitry
2
SHUTDOWN
1
C
(BYPASS)
(1)
100 kΩ
Gain = R
F
/R
I
f
c
+
1
2p R
I
C
I
-3 dB
f
c
TPA6211A1
www.ti.com SLOS367D –AUGUST 2003– REVISED JUNE 2011
Figure 31. Differential Input Application Schematic With Input Bandpass Filter
Input Capacitor (C
I
)
Selecting Components
The TPA6211A1 does not require input coupling
Resistors (R
I
)
capacitors when driven by a differential input source
biased from 0.5 V to V
DD
- 0.8 V. Use 1% tolerance
The input resistor (R
I
) can be selected to set the gain
or better gain-setting resistors if not using input
of the amplifier according to equation 1.
coupling capacitors.
(1)
In the single-ended input application, an input
The internal feedback resistors (R
F
) are trimmed to
capacitor, C
I
, is required to allow the amplifier to bias
40 kΩ.
the input signal to the proper dc level. In this case, C
I
and R
I
form a high-pass filter with the corner
Resistor matching is very important in fully differential
frequency defined in Equation 2.
amplifiers. The balance of the output on the reference
voltage depends on matched ratios of the resistors.
CMRR, PSRR, and the cancellation of the second
(2)
harmonic distortion diminishes if resistor mismatch
occurs. Therefore, 1%-tolerance resistors or better
are recommended to optimize performance.
Bypass Capacitor (C
BYPASS
) and Start-Up Time
The internal voltage divider at the BYPASS pin of this
device sets a mid-supply voltage for internal
references and sets the output common mode
voltage to V
DD
/2. Adding a capacitor filters any noise
into this pin, increasing k
SVR
. C
(BYPASS)
also
determines the rise time of V
O+
and V
O-
when the
device exits shutdown. The larger the capacitor, the
slower the rise time.
The value of C
I
is an important consideration. It
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